In recent years display devices which are so called electro optical devices, such as liquid crystal devices and electroluminescent devices and the like, have become widespread as display sections for electronic devices such as portable telephones, portable computers and the like. Furthermore, recently, it has become common to provide a full color display upon such a display device. A full color display upon such a liquid crystal device is provided, for example, by passing light which has been modulated by a liquid crystal layer through a color filter. And such a color filter is made by arranging filter elements of various colors such as R (red), G (green), and B (blue) in dot form upon the surface of a substrate plate which is made from, for example, glass or plastic or the like in a predetermined array configuration such as a so called stripe array, delta array, or mosaic array or the like.
Furthermore, a full color display upon such an electroluminescent device is provided by, for example, arranging electroluminescent layers of various colors such as R (red), G (green), and B (blue) in dot form upon the surface of a substrate plate which is made from, for example, glass or plastic or the like in a predetermined array configuration such as a so called stripe array, delta array, or mosaic array or the like, and sandwiching these electroluminescent layers between pairs of electrodes so as to form picture elements (pixels). And, by controlling the voltage which is applied between these electrodes for each picture element pixel, a full color display is provided by causing light of the desired colors to be emitted from these picture elements.
In the past, there has been a per se known method of using photolithography when patterning the filter elements of a color filter of various colors such as R, G, and B, or when patterning the picture elements of an electroluminescent device of various colors such as R, G, and B. However there are certain problems when using this photolithography method, such as the fact that the process is complicated, the fact that large quantities of the color material or the photoresist are consumed, the fact that the cost becomes high, and the like.
In order to solve this problem, a method has been contemplated of forming a filament or an electroluminescent layer or the like as a dot form array by discharging in dot form a filter element material or an electroluminescent material by an ink jet method.
Now, a method of making a filament or an electroluminescent layer or the like as a dot form array by an ink jet method will be explained. The case will be considered in which, as shown in FIG. 29(a), a plurality of filter elements 303 which are arrayed in dot form are formed, based upon an ink jet method, upon the internal regions of a plurality of panel regions 302 shown in FIG. 29(b) which are established upon the surface of a so called motherboard 301 which is a substrate plate of relatively large area which is made from glass, plastic or the like. In this case, as for example shown in FIG. 29(c), while performing a plurality of episodes of main scanning (in FIG. 29, two episodes) for a single panel region 302, as shown by the arrow signs A1 and A2 in FIG. 29(b), with an ink jet head which has a plurality of nozzles 304 which are arranged in a linear array so as to constitute a nozzle row 305, filter elements 303 are formed in the desired positions by discharging ink, i.e. filter material, selectively from this plurality of nozzles during these main scanning episodes.
These filter elements 303 are ones which are formed by arraying various colors such as R, Q and B and the like as described above in a suitable array form such as a so called stripe array, delta array, or mosaic array or the like. Due to this, in the ink discharge processing by the ink jet head 306 shown in FIG. 29(b), ink jet heads 306 for just the three colors R, G, and B are provided in advance, so as to discharge the single colors R, G, and B. And a three color array including R, G, and B or the like is formed upon the single motherboard 301 by using these ink jet heads 306 in order.
On the other hand, if a plurality of panel regions 302 are formed upon the motherboard 301, then it has been contemplated to form the filter element 303 at high efficiency by using an ink jet head of elongated form so that the ink jet head is positioned along substantially the entire extent of the widthwise dimension of the motherboard 301, which constitutes its widthwise direction with respect to the main scanning direction of the ink jet head. However there is the problem that, if a motherboard 301 is utilized whose size is different from and does not correspond to the size of the panel regions 302, every time this happens, a different ink jet head comes to be required, and accordingly the cost is increased.
Because the ink jet head has a mechanism in which ink is pressurized by a pressing means, for instance a piezo electric crystal, it is necessary wirings through which signal to drive the piezo electric crystal passes. According to the above necessity, a head device which comprises a board on which a ink jet head and a connector by which a circuit for driving the ink jet head are integrally mounted is utilized.
However, it is necessary to consider a working efficiency in wiring the ink jet heads, a layout of the head devices so as to obtain a desired print pattern, and an noise prevention in designing an arrangement of the head devices.